Transducers can be utilized in numerous applications to measure a broad range of environmental conditions. Pressure transducers are often used in machines, for example, to monitor various pressures associated with the machine, and to provide control signals for safe and efficient operation of the machine.
Certain pressure transducers can include piezoresistors arranged in a Wheatstone bridge circuit and coupled to a diaphragm. Upon the application of pressure, the sensor's diaphragm may deflect slightly, thereby producing an output voltage proportional to the applied pressure. The transducer response to the pressure stimuli may be a linear relationship, having a certain slope and intercept that can vary depending on numerous factors, including diaphragm stiffness, manufacturing variations, piezoresistive element configurations, circuit component tolerances, temperature, etc.
The transducer response as a function of the exerted pressure can be adjusted or altered during the manufacturing process and before the transducer is hermetically sealed. For example, specific components can be selected and installed within the transducer to provide a customized or desired output response. However, hermetically sealing the transducer typically precludes any additional adjustments to circuit components or values.
In applications for which additional adjustments to the sensor response is needed in the field, the body of the transducer can be designed to include holes for accessing and adjusting potentiometers and/or switches within the internal circuitry of the transducer. In such designs, screws and o-rings are typically utilized to close the access holes after the adjustments, and during operation of the transducer. However, such screw holes can compromise the sealing and reliability of the transducer. For example, sealing failure can occur due to loose or incorrectly tightened screws and/or damaged o-ring seals. This is a major shortcoming of the conventional transducer design. Another shortcoming of the traditional design is that there is no simple and immediate indication that the adjustments are set correctly. For example, an operator can change the settings of these adjustments, either maliciously or mistakenly, resulting in severe degradation of the performance of the system.
There is a need for a sealed transducer that can have its output adjusted without compromising the reliability of the transducer.